創建一個類對象列表以將它們與另一個類對象進行比較 (creating a list of class objects to compare them with another class object)

一個例子是：

我想這樣做：

if(something1 instanceof something2)

帶有一個List 的“something1's”，以便能夠像這樣遍歷它：

for(int i= 0 ; i <= list.size; i++) 
{
  if (list.get(i) instanceof something2)
    doSomething();
}

參考解法

方法 1:

You can compare classes using equals() method, this method will check if the class is exactly the same.

So you first put classes in a list (assuming you have classes Foo and Bar and a list is List<Class>):

list.add(Foo.class);

And then you iterate over it and do comparison like this:

if (list.get(i).equals(Bar.class))
    doSomething();

方法 2:

Class class provides API to do instance of like check:

Class numClass = Number.class;
List<Class> classes = Arrays.asList(Integer.class);
...
if (numClass.isAssignableFrom(classes.get(i))) {
    doSomething();
}

方法 3:

Using generic lists and class Class:

List<Class> classes = new ArrayList<Class>();
classes.add(Integer.class);
classes.add(String.class);
classes.add(MyClass.class);
//...

for (Class myClass : classes) {
    if (myClass.equals(MyOtherClass.class)) {
        doSomething(); 
    }
}

方法 4:

List of classes can be declared as List<Class> list, e.g.

List<Class> classes = Arrays.asList(String.class, Number.class);
Class testedClass = Integer.class;

If you want to test the exact classes equality use equals.

for (Class clazz : list) {
    if (clazz.equals(testedClass)) {
        doSomething();
    }
}

Or even shorter

if (list.contains(testedClass)) {
    doSomething();
}

But if you need an analogue of instanceof then use isAssignableFrom

for (Class clazz : list) {
    if (clazz.isAssignableFrom(testedClass)) {
        doSomething();
    }
}

isAssignableFrom means that clazz and testedClass are in the same hierarchy and testedClass extends or equals to class

(by Alex Epvp、Krzysztof Krasoń、hoaz、marcellorvalle、Evgeny)

參考文件

1. creating a list of class objects to compare them with another class object (CC BY‑SA 2.5/3.0/4.0)